Refining of mineral oils by means of alloys or loosely bound compounds of alkali metals



1933. E. c. WILLIAMS ET AL 1,939,339

REFINING OF MINERAL OILS BY MEANS OF ALLOYS QR LOOSELY BOUND COMPOUNDS0]? ALKALI METALS 7 Filed Aug. 10. 1929 Trear'ed 02/ Our/cf Wafer Spray/5 D/sperser 9 I I Coo/er Reduc/hg Wash Tower LG/V 4 4 Treafing Tower 2*Preheafer Gauge Mercury Pas/hue Co//e cror E/ecfro/ r/c Alma/90m Pump 7Mercury 5 forage Ama/gam Ol/ [/7 er Sforage [Nvs/vToRs EVAN CL/FFOPD lMum/ws HERBERT PETERAf/GLSTLCS GRULL 5v THE/R ATTORNEY:

Patented Dec. 19, 1933 UNITE ST REFINING OF MINERAL OILS BY'MEANS FALLOYS OR LOOSELY BOUND COMPOUNDS OF ALKALI METALS Application August10, 1929. Serial No. 384,942

'iClaims. (Cl. 196-23) This invention relates to the refining of mineraland other oils and particularly to the sweetening of cracked productsfrom petroleum, in future referred to as cracked distillate. Theinvention consists in treating the mineral oil with loose compounds ofan alkali metal,- or mixtures of such compounds, preferably in acontinuous process.

These compounds are defined by the character? istic that they aredecomposed by water to the hydroxides of the alkali metal used. Suchcompounds are, for instance, the amides, alcoholates, amalgams, oralloys of alkali metals.

Further features and advantages of our invention will appear from thefollowing description of one method of carrying the invention intoeffect. It will be understood that we do not limit ourselves to thedetails of this particular method of using our invention, but we extendour claims for the principle of our invention as far in scope andequivalents as thestate of the prior art will allow.

The present invention is applicable to many oils, especially mineraloils such as petroleum oils or oils derived from coal or shale, but wewill describe it particularly with reference to the treatment'of crackeddistillate obtained by crack ing from petroleum oils, which is one ofthe most difficult petroleum products to refine.

We found that when metallic sodium was placed in cracked gasoline offoul odour, it became coated, in the course of days, with deposits ofgum-like resins and other solid material, indicating a marked reaction.while the odour of the gasoline improved.

The cost of metallic. sodium, and still more, the danger of usingmetallic sodium in a refinery (sodium reacts violently with water, andthe hydrogen evolved ignite spontaneously), makes its use quite out ofthe question. 7

We therefore investigated the possibility of using loose compounds ofsodium or' other alkali metals which would show a similar effect to thatof. metallic sodium on the mineral. oils without its disadvantages.We-foundsuchcompounds as the ami'd'es, alcoholates, amalgams oralloys ofalkali metals to be refining agents for mineral oils. This refiningaction is due partly to removal of sulphur compounds and otherundesirable substances which form compounds, with the alkali metal, andpartly to the polymerization of unstable and therefore undesirableconstituents to form gums or resins. These polymerized gums or resinsare in part precipitated in the form of sludge together with the alkalimetal compounds formed during the process as mentioned above,

features described in this. example:

and in part, remain dissolved in the oil. Pref.-

erably we redistill the oil treated according to our invention in orderto free it from these polymerized and high boiling gums. r

. The following is an example of one of the most useful methodsofapplying ourinvention forthe refining of mineraloils by the action ofalkali metal amalgams. It may be understood weare notconfining-ourselves'to any'of theparticularv .A solution of sodium orpotassium amalgam in mercury is usedlas refining agent. Theconcentration of .the amalgam is keptlow enough tokeep'. this solutionliquid at thetreating temperature. 'I'he'mineral oil can be treatedatnormalor' at" elevated temperature, preferably around 100 C. at whichtemperature the velocity of the reaction is sufficientlyhigh. ,Ifthetemperature is allowed to rise higher tl'ia n' 150 C; the refiningaction is less eifective 'andthere is excessive reaction be tweenmercury and the sulphur compounds in the oil, as a result of whichmercuric sulphide is formed. As the temperaturerises this compound isformed in increasing amounts thus making the recovery of the'usedmercury more complicated and the process less practicable. We there:fore prefer to operate at a temperature not exceeding 100C.

At a treating temperature of 100 C. a solution of amalgam'in mercurycontaining more than 1.5% sodium or 2.0% potassium is liable to ,crys:tallize and thisfrenders impracticable any circulationof the amalgamsolution as described hereunder. 'We therefore operate witha solution ofamalgam containing not more'than 1% sodium and preferably 0.7%. Whenpotassium amalgam is used it is possibleto operate with a'slightlyhigher concentration of the alkali metal; v

The use of a liquid solution of'alkali metal r amalgam in mercury isadvantageous from sev-' eral points of View: first, it can bemanufactured cheaply by the electrolysis of alkali metal salt solutions,which manufacture is thoroughly established in the chemical industry.This avoids the necessity of preparing the amalgam by dissolving metalicsodium or potassium in mercury, a 'method which, because of fire hazard,is too dangerous to employ in an oil refinery and because of the highprice of "these metals, is entirely uneconomical as a means of refininggas oline; Second, the diluted amalgam does not re act vigorously withwater, and never such rate as to ignite the hydrogen evolved. Third, thedilute' amalgam, being in the liquid state, may bev circulated in acontinuous plant; as a liquid in to the oil and does not become coatedwith a layer of polymerized gums; consequently, the amalgam reacts morereadily and more completely than a solid compound of'similar nature. Asa consequence. of this more ready reaction, the. refining in our processis completed in to minutes, whereas with solid metals 'or alloys in amanner wellknown to those 'skilledin' such operations, to agitate-theamalgam-on the sevthe refining may take several hours.

I For the sake of brevity this solution of. alkali metal amalgam inmercury as specified above will be referred to in the future as.amal'gam.

It will be understood that there are many different ways of carryingthisinvention into practice: all of which have as their object bringingthe amalgam or other alkali metal compound into:

intimate contact with the. mineral oil to be treat ed in a continuousand preferably counterecurrent manner.

For example, the amalgam or other alkali metal compound may bebrought'into reaction by agitating it in contact with the crackeddistillate in a single vessel or in a number-of vessels arranged inseries throughwhich the amal gam and cracked distillate arernadeftojpass in, a counter-current manner.

Alternatively, such a series of vessels' may be replaced by a towerfitted with a number of superimposed'trays,down which amalgam flows fromtray to tray, and up which the distillate to be treatedpasses,arrangement. being made i 1 treated iscaused to flow. I

cathodev is so arranged that it is'in'contact on one handWith'electrolytaand on the other with.

'the mineral oil. v V

reacts; directly with the cathode, which latter is caused to flow.

Alternatively, the mineral oil to be treated may be made to react withthe amalgam in a compartment adjacent toorforming an integral part I ofthe electrolytic cell in whichthe mercury the mineral oil to be treated;The mercury amalgam cathode may be agitated'in any preferredway-in orderto facilitate reaction with In this manner the mineral oil provides 'asupply ofsodium continuously from the electrolyte to the oil, a .The]attached drawing illustrates enr'iployed' with good results for theapplication of our invention, using the principle of atomizing amalgaminto the upper part of a vertical treat ing tower, up which the mineraloil tobejtreated is byno means the final form of our plant, as longerpractice probably will require improvements and alterations Without,however, changing the principle of our invention.

The mineral oil used in this example is a cracked distillate, previouslysubjected to the normal acid and soda. wash treatment, and containingabout 60% of gasoline fraction. The appropriate. sections of theapparatus must therefore .be capable of withstandingthe pres.-

sures' of 100-200 lbs. per sq.'inch developed at the treatingtemperature. r

The apparatus consists mainly of l, preheater;

2, treating tower; 3, cooler; 4, water washtower;

I more or less diagrammatically an apparatus which we have It Will beunderstood that'this ,ceed 1.'0% oftheamalgam solution? V 1,939,839.motion it continuously presents affresh surface 5, separator for sludgeand mercury; 6, mercury storage tank; 7, electrolytic cell; 8, amalgamstorage tank; 9, amalgam disperser; 10, mercury residue collector.

g In the operation of thi's 'apparatus the cracked distillate to betreated is introduced through line 7 '11 to pump 12 and pumped throughpreheater 1,

which may consist in part of a heat exchanger,

1 to treating tower 2, which may also be heated.

It is met in this tower by a descending counter flow of amalgam. Thetreated cracked distillate leaves the top of tower 2 by a side arm 13,and passes to the cooler 3, beyond which, at valve l4 the pressure isreduced to approximately atmospheric. It then passes to the bottom ofwash tower 4,- where it is washed in counterflow by water or dilutecaustic soda from spray 15. The Wash; water and sludge whichlattercontains a little finely divided mercury or mercury sulphide'are'collected in receiver 10, while the treated oil leaves by line 16.The sludge from receiver 10 is worked up by any suitable process, as,for instance, by, filtering, centrifuging, roasting, etc. to recover thesmall'amount of mercury which it contains; The sludge collectedatsepar'ator '5 is separatelywashed with water andthen subjected to thesame recovery process. Any oil whichseparates during the washing of thissludgefis re turned to the cracked "distillate storage. Thetreatedcracked distillate is distilled, preferably" with open steam, for'thepreparationfof gasoline of suitable endpoint, and the separation of anyhigh boiling polymerized products.

7 Mercury stored'in tank '6 is passed "to electrolytic cell- '7, wheresodium amalgam is formed.

Thispasses by gravity to storage tank 8, whence pump .17 passes itftothe amalgam disperser 9,

from which thedispersed amalg'ainifalls directly into treating tower 2."The mercury, denuded of sodium by reaction with the undesirableconstituents of the cracked distillate, collects at the bottom oftower2, and is returned to storage tank 6, through the sludge separator5. 7

In actual operation, more parts and instruments may be added which havebeen omitted here for the clearnessjof the description, as theycanreadily be added by those skilled in'the artljj a The outletofthedistillate from tower 2 is so arranged by ineansoi the side-armlsth'atnone, or at worst very little, of the heavyamalgam can pass outof the towerwith the distillate." V

. The oils treated by any methods of our inven-' tion aredistinguished'by' their pleasant odour,'. water white colour,'-colourstability in sunlight or darkness, and negative doctor test; In theserespects especially, the cracked gasoline treated by ourprocessis'far'superiorto cracked gasoline refined by the usual processes.

We claim 'as our invention: 1

1., A process for the refining of' o'ils cQmprisingtreatingithe oil withalkali metal amalgams whose alkali metal content does not'exceed 1%" ofthe amalgam. v

i 2. A process for refining mineral oils, comprising'treating' themineral oil with sodium amalgam whose sodium content does not exceed 1%of the anti'a a i J 1 3. Aj'process for the refining, of cracked pe-'troleum oils, comprising treating the oil with a solution of sodiumamalgam in m'ereurm the "'lsodium content of which solution'does notdium content of which solution does not ex-.

ceed 1% of the amalgam solution, at about 100 C.

7. A process for the refining of oils comprising treating the oil withan alkali-metal amalgam whose alkali-metal content does not exceed 1% ofthe amalgam, at about 100 C.

EVAN'CLIFFORD WILLIAMS.

HERBERT PETER AUGUSTUS GrROLL.

